Vehicles equipped with an automatic transmission often include a shift control lever mounted on a console, the dashboard, or the steering column of the vehicle. A vehicle operator may manually move the shift control lever between shift lever positions. The shift lever positions indicate particular transmission ranges (park, reverse, neutral, drive 1, drive 2, drive 3, etc.). Movement of the shift lever into a particular shift lever position causes the transmission to be operated in a particular gear or set of gears.
For example, the shift control lever includes mechanical linkages that couple to the automatic transmission. The mechanical linkages cause the automatic transmission to operate in the particular gear or set of gears. For example, when the shift control lever is moved to the park position, a mechanical linkage activates a parking pawl device or other device of the transmission. The parking pawl device locks the movement of the transmission output shaft thereby preventing movement of the vehicle wheels.
In some cases, conditions can occur in one or more of the mechanical linkages that prevent proper operation. The conditions can cause unexpected movement of the vehicle. For example, when the shift control lever is in the park position and when a condition exists in the mechanical linkage between the shift control lever and the transmission, the vehicle may roll forward or backward (referred to hereinafter as vehicle roll).
Accordingly, it is desirable to provide methods and systems for preventing vehicle roll. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.